Electric wave signaling system



Dec. 13, 1927.

F. M. RYAN ELECTRIC WAVE SIGNALING SYSTEM Filed Sept. 22, 1925 3 .w m M: mmum m r J a v 6 6 6 J a Patented Dec. 1927.

UNITED STATES PATENT OFFICE.

FRANCIS M. RYAN, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRIC "WAVE SIGNALING SYSTEM.

Applicition filed September This invention relates to electric wave signaling systems. and more particularly to means for controlling the power transmitted by space discharge repeaters. r

It is well known that when a space discharge tube, which is adjusted to deliver a certain space current. is supplied with alternating current waves, the direct current component or average value of the space current may increase or decrease or, in other words. the average .value of the space current may be changed. This change occursin part by virtue of the fact that the characteristic of the tube is not linear for all values of grid voltage and the character of the change, i. e. increase or decrease depends upon the part of the characteristic curve at which operation is taking place.

Aresult of this phenomenon. in signaling systems, for example radio telegraph trans:- mitters as ordinarily adjusted. that. during the time that signal waves are supplied to the power amplifier. the space current is likely to be much larger than when the waves are interrupted. It the signal waves are controlled l) a telegraph kcy as is done in the sO-Callml (\Y or continuous wave method .of signaling, the plate current of the amplifier will vary in an abrupt manner. 'l he consequence is that changes in the frequency of transmitted waves are produced. and current surges in the space current circuit are set up. 'lhcse surges cause great changes in the demand upon the source supplying's nice current to the amplifiers. as well as increase the danger of disruption oi insulation. 7

An object oi the invention is to prevent undesired fluctuations in the current supplied to a space dischargc tuhc.

A further object to maintain the average value of the space current of a space discharge tulic substantially con tant during changes in the voltage supplied to its input circuit,'

Another object is to control signaling waves and a polarizing voltage supplied to a space discharge amplifier to maintain the average space current of the amplifier substantially constant.

A further object is to so control the voltage supplied to the input circuit of a space discharge repeater as to prevent distortion 22, 1925. Serial No. 57,809.

of signal waves transmitted therethrough caused for example, by a change of fre-- quency.

A still further object is to prevent sudden changes in the impedance otthe space path of a space discharge amplifier supplied with interrupted signal waves.

A feature of the invention is a means controlled by a signal source for supplying a polarizing potential to a space discharge amplifier during signaling to maintain the space current of the. amplifier at a fixed average value whether signals are transmitted or not.

Another feature is an arrangement c0- operating, with a source of. polarizing potential for controlling the power supplied to a space discharge amplifier and for adjusting the source of polarizing potential to correspond to the power adjustment.

A further feature is an arrangement of space discharge repeaters intandem and a common control means associated with polarizing potential sources forsaid repeaters, by the operation of which the impedance of the space paths of the repeaters may be simultaneously varied in the same or opposite senses.

By the invention the broad result is accomplished of controlling-the load current of a space discharge device by supplying to its control electrode a suitable voltage to compensate for the effect produced upon the av rage space current by the application or removal of signal or other alternating ca1' rcntwaves. More specifically, the impedance of the tube is adjusted so asto maintain steady and constant the average value of the space current. vMeans, adapted to remove the compensating voltage when the signal wave voltage is supplied to the space discharge device, is also provided.

A collateral feature of the invention is the combination of a plurality of space discharge repeaters in tandem rovided with common control means for increasing the space path impedance of one tube and simultaneously decreasing the impedance of the space path of another tube, so that the average space current of one tandem tube is maintained substantially constant.

In practice, the invention may be embodied in a radio telegraph transmitter includtil) ing a space discharge oscillator adapted to supply high frequency wures to a power space discharge amplifier. A telegraph key is adopted to include or exclude respective resistances in the input circuits of the omillator and amplifier so that the oscillations may be stopped and started for signaling purposes and, synchronously therewith and in the same order. polarizing voltage is alternately removed iro'm and, rcsupplied to the amplifiercontrol electrode to maintain its average space current constant.

In the figure of the drawing. a radio transmitting system which embodies the. invention is illustrated. V

A detailed description of'the radio transmitter shown in the drawing follows.

This transmitter includes a space dis charge oscillator arranged to supply high frequency oscillations to a, power 8 ace dis charge amplifier 16, which 18 coup ed to an antenna 17.

The oscillation generator 15, which is of the general type disclosed in U. 8. Patent h o. l, i24.537, dated April 12, 1927, comprises u space discharge tube 22. having an input circuit connected to its-control electrode and cathode. and an out mt circuit, connected to its anode and catho e, a teed-back path connee ted to its anode and control electrode, end a space current supply path also connected to its anode and cathode. Clhe input circuit extends from the control electrode through high frequency choke coil 23, resistance 23', resistance 24, through the secondary Winding of transformer 37 to the cathode of tube 22. which is grounded. l t-assistance M is supplied with direct current tron e. rectifier 25, which is in turn supplied current through a tra'nstormcrfitl, connected to an alternating current source, herein shown, by Way of example, as 9. generator 2'3.

flpace current is supplied to the tube 22 from the rectifier The space current circuit may be traced from the anode through high frequency choke coil 28. inductance 2t lllflli frequency choke coil 30, low :lrcipiency choke coil 31. rectifier resistuncc '24. the winding 37 to the cathode oi the tube.

The alternating current output path of l 22 extends from its anode tbrou h e coil 28 coil 29 shunted by the conand 36 to ground. thence to com 38 and the cathode of the tube, Choice coil 31 cooperates with a condenser to suppress undesired variations in the output current from rectifier whereby they are prevented from producing undesired variations in the oscillator}' currents. Choice coil prevents the passage of high Zrequency Waves through the rectifier 25 and associated circuits.

IFOtentiid across resistance 2% is epplicd masses to the control electrode of tube- Resistonce 38 is arranged in shunt to the spsce path of tube 52:2 and functions to maintain a continuous flow of current from rectifier 25 through resistance 24, regardless of variation in the impedance of the space path of tube 22.

An oscillatory circuit comprising adjust; able inductance :29. adjustable condenser 35 and fixed condenser 36. is suitably connected to the electrodes of tube 22.. This circuit determines the frequency of oscillations produced by the generator. including the tube 2:2. The frequencv of these oscillations may be varied by adjusting;- the inductance 25). or variable condenser 35. or both. The alternating polertiul dillcrcncc at the terminals of conden er 35 is impressed upon the input electrodes of tube .52 and is adjusted to u suitable value by variation of the condenser capacity.

flbe cathode of tube 22 is adapted to be h ited by current from a secondary winding of transformer 37. The primary Winding of this transformer is connected to the gencrutor 27. The mid-point of the secondary winding is connected to ground and its opposite halves are shunted by condensers 38 having equal capacity and low impedance for high frequenc waves.

Connected to the con cnser 36 of the oscillutory circuit 29, 35, 36 is a coupling path including a condenser 39 in series with resistances 40 and 40. The waves of potential difference on the pistes of condenser 36, produced by the oscillations therein are transmitted to the coupling path and thence too to the input circuit of tube 44. This input circuit extends from the control electrode of tube 44 over the path: contact 42 of switch 43, resistance 40', resistance 46, through condensers 33 in shunt to secondary winding of transformer 37 to the cathode.

The resistance 40 is common to the high frequency output circuit of tube 22 and the input circuit of tube 44 of power nmplillolk 16. The high frequency voltage across this resistance is supplied to the control electrode and cathode of tube 44.

The control electrode and tbc cutbodeof tube 44 are also connected by a path including a condenser 45 adapted to prcreu' the production of parasitic oscillations .in' the circuits of the amplifier tube. This condenser renders the. in at path of tube 44: capacitively reactive -or all frequencies at which detrimental oscillations might otherwise be generated. The function of this condenser is to so shift the phase of the energy supplied from the output to the input circuit. of the tube relative to that traversing the inputcircuit that sustained oscilla- V tions are not produced.

"The space current circuit of tube. 44 may 47, choke coils 48 and 49, rectifier 50, resistsince 46, second'a winding of transformer 37 to the catho e. The amplifier output circuit is grounded at theterminal of resistancc 46 which is connected to rectifier 50.

described in connection with tube 2;.

A resonant circuit. including adjushablc inductance 47 and an adjustable tuning condenser 52. is. connected to the anode and cathode of amplifier 16 and is coupled to the antenna circuit 17 by an adjustable coupling condenser 53. Blocking condenser 54 is provided to exclude direct current from the resonant circuit. and a choke coil 55 servesto confine the direct current potential difference to condenser 54 and to prevent the accumulation of a charge in condenser 53 to thereby permit the use of a condenser which is simple in design and relatively inexpensive to manufacture. This choke coil, however, is ofhigh impedance for high frequency waves and accordingly waves of this frequency atv high'voltagc are impressed across the couplin condenser 53, whereby the energy thereo is supplied to the antenna. The antenna circuit includes a loading inductance 56 in series with a coupling condenser 53 and is connected to ground.

For signaling. purposes a telegraph key 66 is included in a series circuit with the winding of a relay l2 and a direct current source 56 represented as a generator.

The switch 43. which by means of its arnr 12 serves to adjust the voltagc of waves supplied by tube 22 to tube 4t.'a.so has a second contact 42 included in circuit with the armature 10 and contact 11 of relay 12. A resistance 13 may be included'in this circuit by moving switch 413 to its second contact. Armature 10 and cooperating contact 11 of relay 12 are adapted ,to shortcircuit a large portion of resistance 24. and armature 10 and contact. 11 are adapted to short-circuit or connect a low resistance. shunt about ltsistulice, -16. which is germanentlyshunted by a fixed condenser 14.

The condenser 14 is designed to provide a maintain the impedance of the space path of tube 22 so high that oseilhitions cannot be generated in the system including this tube. Likewise, the drop in potential across resistance 46. which is included in both the input and output circuits of tube 4-4, is ap- 70. plied to the control electrode of the amplitier, when the armature 10 opens the contact 11, toincrease the impedance of the space path of the amplifier. Relay 12 is arranged to cause armature 10 to open its contact with 11 upon operation of the relay, and

to simultaneously cause armature 10' to engage its contact 11.

\Vhen resistance 2-1 is short-circuited by the armature 1t) and its associated contact, oscillations are established in the generator .15 and are supplied to the input circuit of. the amplifier 44. These oscillations are transmitted through the amplifier, the resonant circuit 47 and 52 and coupling condenser 53 to the antenna 17, Therefore, by operating telegraph key 66, the generation oft oscillations in tube 22 may be controlled in accordance with signals.

As already explained, when oscillations are supplied from generator 15 to tube 4- the average value of the space current betwcen'thc anode and cathode oi the tube 4-4 is ordinarily increased. in part at least. by virtue of the non-linear characteristic of the tube.

In order to maintain the average value of the amplifier space current substantially constant whether key 66 is opened or closed. that is whether oscillations are or are not supplied to the amplilier input circuit. the resistance 46 adapted to be in luded in the input circuit of the amplifier and excluded therefrom by the armature 1'6 and contact 11. The potential supplied by resistance 1 46 to the control electrode of the amplifier is such as to change the impedance of the space path and reduce the direct current component of the space current to the value which it normally has when no oscillations 11. are supplied to the amplilicr. I

3y virtue of this action abrupt cbaniic in the space current are prev nted and the production of surges in space current which cause large changes in the load upon rcctilier 56. are prevented.

This invention has been descri crbin connection' with a particular en'tbodinrcnfor thepurpose of describing. its operation but it is to be limited only in t1t'('()l(l:lll( with the scope of appended claims. A

If tube 44 is so adjusted that when oscillations are supplied to its control electrode I the average space current is reduced instead of increased, the proper compensating voltage may, be applied by making armature it) normally out of engagement with contact 11. The armature would then close the contact when relay 12 is operated upon theglo sure of key 66. By providing resistance' tii.

of suitable value the compensation may he ell'cctcd with the dillcrence in operation that resistance it; applies a negative potential to the control e ectrodc oi tulle 44 when no waves are supplied thereto hut this potential is removed when waves are supplied thereto.

What is claimed is:

1. in comhination. a space discharge repeater. a source for supplyinghigh frequency waves to said repeater, means For contro ling said waves in ac ordance with signals. and means affecting the space path impedance of said repeater for maintaining its average space current substantially constant during signaling.

2. In comhinalion. a space discharge repeater having input and output circuits. a sour e for supplying signal waves to said input circuit. a control means for said source. and a. resistance common to said input and output circuits controlled by said means for maintaining the average flow of current in said output circuit substantially constant. 3. A space discharge repeater having an 'nput and an output circuit, means for interunttcntly supplying waves to said input circuit. the current in said output circuit being atl'ectcd by said waves, a resistance in said circuits. and means operated in synchronisiu with a supply of waves to said input circuit to intermittently short-circuit said resistance to compensate for a certain ett'ect of said wavesupon said circuit.

4. A space discharge repeater having an input and an ont-put'circuit, an impedance network included in both said circuits, a source of signals, and'means controlled in accordance with said signals for connecting a shunt path about said network.

5. A plurality of space discharge repeaters in tandem each having an input and an output circuit, separate impedances in said input circuits. a source of signals, and means for alternately shunting said impcdances in accordance with signals.

6. A plurality of space discharge repeaters each having an input and an output circuit, separate inipedances traversed by direct current included in said input circuits, a source of signals. and a relay connected to said source and controlled by signal impulses therefrom, adapted to' alternately shunt one of said iinpedances and then the other.

7. In combination a plurality of space dis: charge repeaters each including a cathode, anode and control electrode, means for coupling an anode and cathode of one repeater to'the control electrode and cathode of another repeater, a resistance connected to a control electrode of each repeater, said resistances being traversed by dh'ect current, and means for short-circuiting at least a portionof each of said resistances in accordance with signals to maintain the average space current in one of said repeaters suhstantially constant.

8. in a radio transmitting system. a space discharge oscillator and a space discharge amplifier coupled intandem. an input circuit for said oscillator and an input and output circuit for said uniplilicr. said input circuits including impedance control elm-trodes. nuans in said input circuits for impressing a polarizing potential upon said electrodes, a relay controlled by a telegraph key to control the potential impressing means of said oscillator for starting and stopping oscillations and to control the potential impressing means ot said amplifier to maintain the average value of its space current suhstanlially llXvtl.

.A vacuum tuhe re -icatcr having an in put and an output circuit. an impedance network comprising a resistance and condenser includtul in both said circuits. a source of signals. and means controlled in accordance with said signals for connecting a short circuit path ahont said network.

it). In 'a radio transmitting system an oscillato' and an amplilirr coupled in tandem by means including a switch and a potenliouwtcr rarialde by said switch, an input circuit tor said ainplilicr and a resistance included therein, a shunt path for said resistance including a relay armature and contact, and a contact of said switch adapted to change the impedance of said shunt, path in accordance with variation of said potentiometer. whereby the potential supplied to the input circuit of said amplifier may he adjusted.

11. in combination a space discharge oscillator and a space discharge repeater each having an input and a space current circuit, a resistance included in each of said input circuits, one of said resistances heing included also in the space current circuit 0t" said repeater. and means for intermittently and "alternately shunting a portion of said resistances to vary the impedance of said oscillator for controlling the. generation of oscillations and to maintain the impedance of the space path of said amplitier substantially constant.

12. The method of operating a space discharge repealer to maintain a constantaverage space current which comprises, impressing upon the control electrode of said repcater, wares to be amplified and simultaneous- 1y impressing thereon a steady polarizing voltage of such'maguitude as to compensate for the change in the average control electrode potential occasioned by the waves to be amplified.

In witness whereof, I have hereunto subscribed my name this 3rd day of September FRANCIS M. RYAN.

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